Shows a red dashed line in front of your own boat, with present COG and ends in a small square, which represents where you will be in the set number of minutes, with the present speed. 6 minutes is a good starting value for piloting. If your vessel has a SOG of 10 knots the dashed line will be 1 nautical mile long. 60 minutes makes sense on a coastal passage and 24 x 60=1440 minutes on longer blue water passages.

If a heading sensor is available and outputs an nmea data stream, this is shown as a finer line with shorter dashes ending in an open small circle. The length is set in Nautical miles.

The width of the COG Predictor can be adjusted in the opencpn.ini configuration file. Find the line below and adjust the value.

OwnshipCOGPredictorWidth=3

Warning: Don't edit the opencpn.ini (opencpn.conf) file when OpenCPN is running.

The following options are available for Ownship:

This will use the icon that comes with OpenCPN, unless you have installed your own icon, “ownship.png”. More about installing your own icons in Marks and Routes .

This option will adjust the size of the default icon, depending on your settings. When using this setting, the dialog expands and five more options related to the size of “ownship” become available. See picture below

The overall length of Own Ship in meters

The overall width of Own Ship in meters

The distance in meters from the bow of Own Ship to its GPS antenna

The distance in meters from Own Ship's center line to its GPS antenna. Use a positive value for an offset to starboard and a negative value for an offset to port.

The size of the Own Ship icon on the screen. Default is set to 1mm.

Works the same as the previous option with the exception that ownship is a somewhat boxy, computer rendered ship. It's currently not possible to change the vector-own-ship.

The dot represents the set location of the GPS.

These show up as red rings centered on your gps position and can be useful in different circumstances, such as keeping clear of dangers. The settings are, hopefully, intuitive.

Once the number of radar rings are selected, and not equal to “None” the dialog expands, and shows more settings. The Distance Unit for Radar rings is set here, and does not follow the the global settings in Options→Display→Units. The choices are Nautical Miles and Kilometers

Automatic Daily Tracking ensures that the track-points collected throughout a single day (midnight to midnight in local zone time) are stored and managed as a single (possibly multi-segment) track.

If the Automatic Daily Tracking check-box is selected, the “Toggle Tracking” tool will turn tracking on and off. However, on turning it off, the accumulated track will be extended with the previous one if it does not extend into yesterday. Disjoint segments are kept separate, time-adjacent segments are merged into a single segment. Disjointed track segments can be joined through the right-click menu when they are selected in the Route Managers Tracks Tab.

Every Midnight the tracking is turned off and on again automatically to ensure that the track does not span dates. If Automatic Daily Tracking is selected during the day, when some tracks have already been created, only the last one will be merged with future daily tracks.

Assuming Automatic Daily Tracking is on, normally during tracking periods there will be two tracks visible in the Route Manager: the current track (red color track-points on the chart) and the previously accumulated track for the day. After toggling tracking off there will be just one track for this day.

If the timezone needs to be changed, it is a good idea to close OpenCPN application before.

With the manual capability of splitting and extending, the daily tracks can be easily managed at any time.

The daily tracks will be automatically named with the date in the local Time Zone, but can of course be changed manually.

The Automatic Daily Tracks follow the settings in Tracking Precision, see below.

Without Automatic Daily Tracks selected, OpenCPN handles tracks as before.

Shows a 7 to 10m wide highlighting on either side of the track. This is not selectable for individual tracks. The idea of the highlighting is to remind us that following a previous track exposes us to the inherent inaccuracy of GPS, and that the real track followed is most likely within the highlight region, but not necessarily in the middle. And this says nothing about the accuracy of the underlying cartography. For many charts it is prudent to assume at least 1.5 mm inaccuracy using the nominal scale of the chart. For a chart in scale 1:20,000 this translates to 30m.

With track button in the ToolBar activated this setting affects the size of the data saved. It also affects the “smoothness” of the track, though this is only visible when zoomed in to a very large scale. OpenCPN uses smart dynamic tracking, and only uses those track points that actually contributes anything to the track. A straight line track for example is only represented by it's endpoints. This is done by analyzing the track just behind the boat. The process is visible in real time, close to Own Ship. The end result is good track accuracy while keeping the size small.

• Low: Good for offshore passages.
• Medium: Very good for all normal uses.
• High: Only necessary when very tight maneuvering needs documenting.